Accessory Dwelling Units (ADUs) and Junior Accessory Dwelling Units (JADUs)
- What are ADUs?
- New! New laws effective January 1, 2020
- Other recent updates to state laws for ADUs - Includes webinar
- Technical Assistance Booklet - Includes FAQs and sample ordinances
- City and county ADU ordinances and HCD review letters
- Sample materials from cities and counties
- Additional guidance
- External websites (contributors to Technical Assistance Booklet)
What are ADUs?
Accessory Dwelling Units (ADUs) have been known by many names: granny flats, in-law units, backyard cottages, secondary units and more. No matter what you call them, ADUs are an innovative, affordable, effective option for adding much-needed housing in California. HCD is the state’s leader on local ADU ordinances, which — while optional — have grown exponentially in number as more cities, counties, and homeowners become interested in ADUs as one solution to increasing the supply of affordable housing.
What are the benefits of ADUs?
- ADUs are an affordable type of home to construct in California because they do not require paying for land, major new infrastructure, structured parking, or elevators.
- ADUs can provide a source of income for homeowners.
- ADUs are built with cost-effective wood frame construction, which is significantly less costly than homes in new multifamily infill buildings.
- ADUs allow extended families to be near one another while maintaining privacy.
- ADUs can provide as much living space as many newly-built apartments and condominiums, and they’re suited well for couples, small families, friends, young people, and seniors.
- ADUs give homeowners the flexibility to share independent living areas with family members and others, allowing seniors to age in place as they require more care.
What are JADUs?
Junior Accessory Dwelling Units (JADUs) are allowed to be created within the walls of a proposed or existing single-family residence and shall contain no more than 500 square feet. JADUs offer additional housing options. They may share central systems, contain a basic kitchen utilizing small plug-in appliances, may share a bathroom with the primary dwelling, all to reduce development costs. JADUs present no additional stress on utility services or infrastructure because they simply repurpose existing space within the residence and do not expand the dwellings planned occupancy.
New! New laws effective January 1, 2020
The Legislature further updated ADU and JADU law effective January 1, 2020 to clarify and improve various provisions in order to promote the development of ADUs and junior accessory dwelling units (JADUs). These include allowing ADUs and JADUs to be built concurrently with a single-family dwelling, opening areas where ADUs can be created to include all zoning districts that allow single-family and multifamily uses, modifying fees from utilities such as special districts and water corporations, limited exemptions or reductions in impact fees, and reduced parking requirements. Please see the Accessory Dwelling Unit Technical Assistance memo (PDF) for more information.
Other recent updates to state laws for ADUs
Effective January 1, 2019
As of January 1, 2019, homeowners who created accessory dwelling units (ADUs) without the required building permits may have the opportunity to bring their ADUs into compliance. For ADUs that were constructed without building permits, local building officials now have the option to inspect an ADU and apply the building standards that were in effect at the time the unit was constructed. This bill: SB 1226 (Bates), adds Section 17958.12 to the California Health and Safety Code Opens in New Window , and with application of appropriate building codes, may allow issuance of a building permit for the residential unit.
Webinar : Recent Legislation "Nuts and Bolts"
Technical Assistance Booklet
Information for cities, counties, other local government bodies, and homeowners interested in adding an accessory dwelling unit to their property.
Please note: The ADU Memorandum booklet is currently under construction to reflect recent changes to ADU law which became effective January 1, 2020.
City and county ADU ordinances and HCD review letters
Cities and counties are not required to create ordinances for ADUs; however, any city/county that does adopt an ADU ordinance, must submit the ordinance to HCD within 60 days.
- Requests for adopted ADU ordinances should be emailed to: firstname.lastname@example.org
- ADU ordinance review letters sent to jurisdictions (XLS)
Sample materials from cities and counties
- California State Fire Marshal (PDF) - Information bulletin regarding sprinkler system requirements.
- CalHFA (PDF) - Bulletin for ADU income which includes anticipated income from planned ADU to qualify for loan to create the ADU.
- California Energy Commission updates for ADU:
- Blueprint Newsletter Issue 123 (PDF) — ADUs and adoption of 2019 energy code, effective January 1, 2020
- New! Blueprint Newsletter Issue 129 January – March (PDF) — ADUs and adoption of 2019 Energy Code: PV (solar panel) Requirements for ADUs
- California Department of Housing and Community Development (PDF) - Information Bulletin providing clarification and outlining provisions of various residential types, ranging from recreation vehicles and manufactured homes to site-constructed California Building Standards Code dwellings.
- For ADUs in Coastal Commission areas:
- New! Implementation of New ADU Laws (PDF) - April 21, 2020
- ADU guidance memo for planning directors in coastal cities and counties (PDF) - April 18, 2017
- ADU guidance memo update (PDF) - November 20, 2017
- ADU Update: Early Lessons and Impacts of California's State and Local Policy Changes (PDF) – Provides an overview of ADUs as a housing solution for California. Covers recent policy changes at the state and local level, California's progress to date, and remaining barriers. Written by David Garcia at the Terner Center (U.C. Berkeley), December 2017
- Accessory Dwelling Unit Policies in Monterey County: An Opportunity for Greater Impact (PDF)
You'll find additional resources at the following websites, which are hosted by partners who contributed to HCD's Technical Assistance Booklet.
- New! ADU amnesty program, with an ADU idea book and cost estimator, in San Mateo County for existing ADUs constructed without necessary permits and approvals. – ADU amnesty program
- New! Discover the potential for an ADU on your property. Lot and zoning information by simply providing your address – ADU possibilities on your lot
- New! The Backyard Homes Project – This is a "one-stop shop" ADU program in Los Angeles that enables the average homeowner to become a provider of affordable housing.
- New! American Planning Association (APA) webinar for ADU statute updates, effective January 1, 2020 – Technical assistance (TA) presentation addressing the updates to accessory dwelling unit and junior accessory dwelling law, effective January 1, 2020.
- New! ADU Resource Center the American Institute of Architects (AIA)
- Get Ready for Your Backyard Home San Jose
- The ABCs of ADUs (PDF) – A guide to Accessory Dwelling Units and how they expand housing options for people of all ages (from AARP)
- Clovis Cottage Home Program (PDF) – Promotion of infill residential development on qualified properties in the Old Town area with city provided floor plans, building permit package and fee-waived checked plans
- Accessory Dwellings - One-stop resource about accessory dwelling units. (Portland, OR)
- Everything About Building ADU in Los Angeles - Although the City is still in the process of adopting an ADU ordinance, this fact sheet provides guidance for types of ADU, parking, current building codes, cost estimates, potential rental rates and more.
- Second Unit Resources Center - Although focused on San Mateo County, this website can serve as a great model for other sites. It includes: